Access layoutLocation via public headers

[paroj]

I used to do

program->getUniform(i).getType()->getQualifier().layoutLocation

to get the uniform location declared as:

layout(location = 2) uniform ...

now that the TType definition is gone from the public headers, is there another way to get to it? Or is this something that needs to be added back to the public API?

[arcady-lunarg]

Let me look into this, if there isn't a way to get this only using public headers then we'll have to add some stuff back to the set of installed headers.

[paroj]

just a quick reminder, wondering whether you found something?

[PaulZFox]

Wondering the same. Trying to compile GLSLangPlugin - have checked 1.3.279 and 1.3.280.1 (latest at the moment) versions of Vulkan SDK - there is no definition of TType, just declaration. Compilation failed due that.

Is there any resolution please?

Thanks, Sergei.

[arcady-lunarg]

Would using the spirv-reflect tool help here? Otherwise, does the ShGetUniformLocation() entry point help at all? If not, I think the thing to do would be to expose a new entry point for this.

[PaulZFox]

Arcady, sorry, probably I'm missing smth, but I don't think any tool/utility can help here. The point is: in Vulkan SDK header files ($VULKAN_SDK/x86_64/include/glslang/Public/ShaderLang.h:146 particularly), there is only declaration of class TType and no definition. However, in OGRE sources there are references to TType class members, like:

TType utype; if( utype->isOpaque()) ...

Compiler fails bc TType is not defined anywhere - no class TType member definitions.

Formally, what we have in $VULKAN_SDK/x86_64/include/glslang/Public/ShaderLang.h:146 is the only thing compiler knows 'bout class TType.

Thanks, Sergei.

[arcady-lunarg]

Yes, this is intentional: TType is part of the internal implementation of the compiler and was never really meant as a public interface. Please see issue #3320 for more justification about why we're doing these changes. In particular, I don't envision ever reverting TType to being public. You can vendor glslang in your project if you want and then the publicly installed headers don't matter, or we can work together to define another interface that is more suitable as a public API without as much compatibility maintenance burden.

[PaulZFox]

Thanks, Arcady, for clarifications provided.

or we can work together to define another interface that is more suitable

Frankly, I'm new to Ogre and Vulkan and would prefer @Paroj to comment on that.

Thanks, Sergei.

[paroj]

Would using the spirv-reflect tool help here? Otherwise, does the ShGetUniformLocation() entry point help at all? If not, I think the thing to do would be to expose a new entry point for this

spirv-reflect would probably work, however I would rather rely on the information generated at compile time then extracting the reflection a-posteriori from SPIRV.

The API is mostly there and only layoutLocation is missing. This is probably an oversight as per uniform layoutLocation is specific to the OpenGL target and does not exist in Vulkan.

I will need to check ShGetUniformLocation and report back whether it is a valid replacement.

@PaulZFox in any way the Ogre plugin will need to be updated to work with glslang v14 and require a new Ogre release.

@arcady-lunarg my goal is to get the API I can upgrade Ogre to. However from a distro perspective, there is currently no way to package ogre with GLSLang support and glslang v14+.

[bubbleguuum]

A distro can package the private includes. This is what openSUSE Tumbleweed did, especially for Ogre.

EDIT: they are packaged separately as glslang-nonstd-devel package.

[paroj]

Otherwise, does the ShGetUniformLocation() entry point help at all? If not, I think the thing to do would be to expose a new entry point for this.

@arcady-lunarg I took a look at this and the function is part of the old C interface, while I am using the C++ interface (as recommended in the readme). This means I cannot easily check whether the output of the method is plausible and the C++ interface would need to be extended anyway.